fasl-casemode-mismatch

This is the class of condition signaled when an attempt is made to
load a file compiled in case-insensitive-upper (ansi) into a
case-sensitive-lower (modern) mode image. The blocking is done to
avoid multiple symbols (uppercase and lowercase) intended to be
identical from being created. A restart allows users to load the file
anyway if desired.

The following illustrates what can happen when the condition is
ignored and a file is loaded: